Filter unit

ABSTRACT

A filter unit includes a body portion having a proximal end and a distal end. An engagement protrusion extends from the proximal end. The engagement protrusion includes a first portion that has a first radius of curvature and a second portion opposing the first portion that has a second radius of curvature that is larger than the first radius of curvature. A protruding retention surface is disposed on and extends radially outward from the body portion. The protruding retention surface is adapted to secure the filter unit in a filter head assembly.

BACKGROUND OF THE PRESENT INVENTION

The present invention generally relates to a filter unit, and morespecifically, to a filter unit that includes keyed features forinterfacing with engagement features on a filter head assembly.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a filter unit includes a bodyportion having a proximal end and a distal end. An engagement protrusionextends from the proximal end. The engagement protrusion includes afirst portion that has a first radius of curvature and a second portionopposing the first portion that has a second radius of curvature that islarger than the first radius of curvature. A protruding retentionsurface is disposed on and extends radially outward from the bodyportion. The protruding retention surface is adapted to secure thefilter unit in a filter head assembly.

In another aspect of the present invention, a filter unit includes asubstantially cylindrical body portion having a proximal end and adistal end. An engagement protrusion extends from the proximal end ofthe cylindrical body portion. First and second distinct retentionsurfaces are disposed in the cylindrical body portion. A third distinctretention surface is disposed on and extends radially outward from thecylindrical body portion.

In yet another aspect of the present invention, a filter unit includes abody portion having an exterior wall and having a proximal end and adistal end. An engagement protrusion extends from the proximal end. Theengagement protrusion has a cross-section with only one axis ofsymmetry. A retention surface is disposed on the body portion. Theretention surface is defined by one of a radially extending member thatprotrudes outwardly from the body portion and a groove defined in theexterior wall of the body portion.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art upon studying the following specification, claims, and appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of one embodiment of a water filtersystem of the present invention;

FIG. 2 is a front perspective view of the water filter system of FIG. 1with the water filter withdrawn from the filter head assembly;

FIG. 3 is a top perspective view of one embodiment of a water filter ofthe present invention;

FIG. 3A is an enlarged cross-sectional view of the water filter of FIG.3 taken at IIIA-IIIA;

FIG. 4 is an elevational view of a first side of the water filter ofFIG. 3;

FIG. 4A is an enlarged elevational view of a first side of a forwardcasing of the water filter of FIG. 3;

FIG. 4B is an enlarged elevational view of a first side of a forwardcasing of the water filter of FIG. 3;

FIG. 5 is a front elevational view of the water filter of FIG. 3 withcasings;

FIG. 5A is an enlarged view of one embodiment of a laterally extendingkey member;

FIG. 5B is an enlarged view of another embodiment of a laterallyextending key member;

FIG. 6 is an elevational view of a second side of the water filter ofFIG. 3;

FIG. 6A is an enlarged elevational view of a second side of the forwardcasing of the water filter of FIG. 3;

FIG. 6B is an enlarged elevational view of a second side of anotherembodiment of a forward casing of the water filter of FIG. 3;

FIG. 7 is a rear elevational view of the water filter of FIG. 3;

FIG. 7A is an enlarged cross-sectional view of the water filter of FIG.3 taken at VIIA-VIIA;

FIG. 8 is a top exploded perspective view of the water filter of FIG. 3;

FIG. 9 is a top plan view of the water filter of FIG. 3;

FIG. 9A is a top plan view of the water filter of FIG. 3;

FIG. 10 is a bottom plan view of the water filter of FIG. 3;

FIG. 11 is a top perspective view of one embodiment of a filter headassembly of the present invention;

FIG. 12 is a front elevational view of the filter head assembly of FIG.11;

FIG. 13 is an elevational view of a first side of the filter headassembly of FIG. 11;

FIG. 14 is a rear elevational view of the filter head assembly of FIG.11;

FIG. 15 is an elevational view of a second side of the filter headassembly of FIG. 11;

FIG. 16 is a bottom plan view of the filter head assembly of FIG. 11;

FIG. 17 is a top plan view of the filter head assembly of FIG. 11;

FIG. 17A is a top plan view of another embodiment of the filter headassembly of FIG. 11;

FIG. 18 is an exploded top perspective view of the filter head assemblyof FIG. 11;

FIG. 19 is a bottom exploded perspective view of engaging components ofthe filter head assembly and filter unit;

FIG. 20A is an enlarged side perspective view of engaging components ofthe filter head assembly and filter unit prior to engagement;

FIG. 20B is a side elevational view of a filter unit prior to engagementwith the filter head assembly illustrating the lateral engagement keymember and key slot prior to engagement;

FIG. 20C is a side elevational view of the filter unit prior toengagement with the filter head assembly illustrating the first andsecond guides and the first and second engagement surfaces prior toengagement;

FIG. 20D is a cross-sectional view of the filter head assembly of FIG.20B taken at XXD-XXD;

FIG. 20E is a cross-sectional view of the filter head assembly of FIG.20C taken at XXE-XXE;

FIG. 20F is a partial cross-sectional view of the filter head assemblyof FIG. 20C taken at XXF-XXF;

FIG. 20G is a side cross-sectional view of a filter unit prior toinstallation into a head assembly;

FIG. 21A is an enlarged side perspective view of engaging components ofthe filter head assembly and filter unit during engagement;

FIG. 21B is a side elevational view of a filter unit during engagementwith the filter head assembly illustrating the lateral engagement keymember and key slot engaging;

FIG. 21C is a side elevational view of the filter unit during engagementwith the filter head assembly illustrating the first and second guidesand engaging the first and second engagement surfaces engaging;

FIG. 21D is a cross-sectional view of the filter head assembly of FIG.21B taken at XXID-XXID;

FIG. 21E is a cross-sectional view of the filter head assembly of FIG.21C taken at XXIE-XXIE;

FIG. 21F is a partial cross-sectional view of the filter head assemblyof FIG. 21C taken at XXIF-XXIF;

FIG. 22A is an enlarged side perspective view of engaging components ofthe filter head assembly and filter unit fully engaged;

FIG. 22B is a side elevational view of a filter unit in full engagementwith the filter head assembly illustrating the lateral engagement keymember and key slot fully engaged;

FIG. 22C is a side elevational view of the filter unit in fullengagement with the filter head assembly illustrating the first andsecond guides and the first and second engagement surfaces fullyengaged;

FIG. 22D is a cross-sectional view of the filter head assembly of FIG.22B taken at XXIID-XXIID;

FIG. 22E is a cross-sectional view of the filter head assembly of FIG.22C taken at XXIIE-XXIIE;

FIG. 22F is a partial cross-sectional view of the filter head assemblyof FIG. 22C taken at XXIIF-XXIIF;

FIG. 23 is a front elevational view of the water filter system with thewater filter fully installed into the filter head assembly;

FIG. 24 is an enlarged cross-sectional view of the water filter of FIG.23 taken at XXIV-XXIV;

FIG. 25 is an enlarged cross-sectional view of the water filter of FIG.17 taken at XXV-XXV; and

FIG. 26 is a side cross-sectional view of a filter unit fully installedinto the filter head assembly.

DETAILED DESCRIPTION OF EMBODIMENTS

For purposes of description herein the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the invention as oriented in FIGS. 1 and 3.However, it is to be understood that the invention may assume variousalternative orientations and step sequences, except where expresslyspecified to the contrary. It is also to be understood that the specificdevices and processes illustrated in the attached drawings, anddescribed in the following specification are simply exemplaryembodiments of the inventive concepts defined in the appended claims.Hence, specific dimensions and other physical characteristics relatingto the embodiments disclosed herein are not to be considered aslimiting, unless the claims expressly state otherwise.

Referring to the embodiment illustrated in FIGS. 1 and 2, referencenumeral 10 generally designates a water filter system including a filterunit 12 having a body portion 14 (FIG. 4) having a proximal end 16 and adistal end 18. The proximal end 16 is adapted to be inserted into afilter head assembly 20. A laterally extending key member 22 is disposedon the body portion 14 and adapted to engage a key slot 24 (FIG. 11) inthe filter head assembly 20. An engagement protrusion 26 extends fromthe proximal end 16. The engagement protrusion 26 includes a firstportion 28 having a first radius of curvature and a second portion 32opposing the first portion 28 that includes a second radius of curvaturethat is larger than the first radius of curvature.

Referring now to FIGS. 3-4B, the body portion 14 of the filter unit 12includes a cylinder-like construction having a diameter that is easilygraspable by the hand of a user. A multitude of grasping cutouts 40 aredisposed on the body portion 14 and extend toward the distal end 18 ofthe body portion 14 and are designed to provide a gripping surface for auser to both engage and disengage the filter unit 12 from the filterhead assembly 20. As disclosed in further detail herein, engagement ofthe filter unit 12 typically includes rotational and longitudinalmovement of the filter unit 12 relative to the filter head assembly 20.An internal portion of the filter unit 12 includes a water filter 39having a filtering media 41 designed to filter and clean water thatpasses through the filter unit 12 during use. The filtering media 41includes end caps 42, 43 that secure the filtering media 41 in place inthe body portion 14 of the filter unit 12. The end cap 42 includes anoutlet 44 that relays filtered water out of the filtering media 41 afterthe water has been filtered. Seals 45 prevent cross-contamination ofunfiltered water with filtered water that has passed through thefiltering media 41. As shown in FIG. 4B, the distance A from a distalprotrusion surface 47 of the filter unit 12 to a first seal 74 isapproximately 2.69 millimeters. The first seal 74 and a second seal 76have a thickness B of approximately 2.62 millimeters. The distance Cbetween the distal protrusion surface 47 and the second seal 76 isapproximately 18.69 millimeters, while the distance D from the distalprotrusion surface 47 to a shoulder support 89 is approximately 28.30millimeters. Finally, the distance E from the distal protrusion surface47 to the laterally extending key member 22 is approximately 41.20millimeters. The dimensions noted above are specifically configured tocomplement and interact with the filter head assembly 20, therebyallowing for tight and secure engagement of the filter unit 12 with thefilter head assembly 20.

As readily observed in FIG. 5, the engagement protrusion 26 is centrallyaligned as viewed from the front. However, as illustrated in FIG. 6, theengagement protrusion 26 is offset as viewed from the side. Thus, theengagement protrusion 26 is generally disposed in an offset position onthe proximal end of the filter unit 12. Further, as evidenced in FIG. 5,the outlet 72 is generally aligned with a central longitudinal axis 109that extends longitudinally through the center of the filter unit 12.The laterally extending key member 22 can be constructed in a variety ofshapes. For example, the laterally extending key member can include arectangular shape (FIG. 5A), a cylindrical shape (FIG. 5B), or any othershape adapted to interface with the key slot 24 of the filter headassembly 20. Regardless of the shape, the laterally extending key member22 generally has a width of approximately 2.75 millimeters, a height ofapproximately 2.75 millimeters, and extends approximately 27.73millimeters from the central longitudinal axis 109.

The body portion 14 of the filter unit 12 is defined by a forward casing46 and a rearward casing 48 that are placed in abutting engagement overthe water filter 39 disposed inside the filter unit 12. The forwardcasing 46 may be attached to the rearward casing 48 in any known manner,such as by heat staking, welding, or mechanical fastener attachment.Alternatively, it is contemplated that the body portion 14 could includeone integral casing formed from a single part. The engagement protrusion26 extends from the proximal end 16 of the filter unit 12 and is smallerin cross-sectional area than the body portion 14 of the filter unit 12.The body portion 14 tapers gradually from the proximal end 16 to thedistal end 18.

The illustrated embodiment of FIGS. 3-7 depict an electronic device 50that is disposed on and extends from an outer circumference of the bodyportion 14 between the proximal end 16 and the distal end 18 of thefilter unit 12. In the illustrated embodiments, the electronic device 50includes a protective cover 51 having a triangular-type cross-sectionwith an apex 52 of the triangular-type cross-section extending away fromthe body portion 14 of the filter unit 12. The electronic device 50includes a power contact 54A, a data contact 54B, and a ground contact54C. The data contact 54B relays information pertaining to the filterunit 12 capacity, filter unit 12 usage data, and the number of daysuntil a replacement filter unit 12 is needed. The ground contact 54Cprovides a conducting path to a grounding source, which is independentof the normal current-carrying path of the electronic device 50.

The electronic device 50 is used in conjunction with a smart filtersystem 56 that includes a smart filter board 58 that stores payloadinformation values related to timeout intervals based on hours, minutes,and seconds. These values are used to determine how long a userinterface waits for communication from the smart filter system 56 beforetriggering a replace filter icon. In addition, sync user functionalityis used to trigger a configuration of the smart filter system 56.Reconfiguration of the smart filter system 56 may be used to ensure thatthe application control unit, user interface, and smart filter are allusing the same values. This information is all stored in the smartfilter board 58 on the electronic device 50.

The electronic device 50 may use gold plating, or other conductivemetals, on the contacts 54A, 54B, and 54C. The gold plating ensures agood connection with an extremely low ampere circuit in a potentiallymoist environment. Connector grease, or an equivalent, may be used tohelp isolate the contacts 54A, 54B, and 54C and avoid shorting of thecontacts 54A, 54B, and 54C due to moisture. In addition, the protectivecover 51 is implemented to protect the smart filter board 58 afterinstallation into the filter head assembly 20. This protective cover 51also protects the grease prior to being installed into the filter headassembly 20, and provides electrostatic discharge (ESD) protection. As aresult of the isolated low voltage application in the smart filtersystem 56, the electronic device 50 is safe during the installation ofthe filter unit 12 into the filter head assembly 20.

Referring to FIGS. 3A and 7A, an engagement or end wall 60 of theengagement protrusion 26 is integral with a sidewall 61 of theengagement protrusion 26 and has a concave construction that tapersdownwardly to an end aperture, which constitutes an outlet 72 of thefilter unit 12. A side aperture, which constitutes an inlet 70, ispositioned in the sidewall 61 of the engagement protrusion 26. Forpurposes of description, as viewed in FIGS. 3A and 7A, the filter unit12 is described in an upright position, wherein the longitudinal axis ofthe filter unit 12 is in a substantially vertical orientation. In theillustrated embodiment, an angle α₂ of the engagement wall 60 adjacentto the first portion 28 has an angle approximately 67.7 degrees fromvertical. It is contemplated that the angle α₂ could be as low as 15degrees or as high as 90 degrees. An angle α₁ of the engagement wall 60of the engagement protrusion 26 at the second portion 32 of theengagement protrusion 26 is approximately 51 degrees, although it iscontemplated that the angle α₁ could be as low as 5 degrees or as highas 85 degrees. It will be noted that the degrees and constructions ofthe engagement wall 60 may vary from these specified angles and still bewithin the scope of the present invention. As shown in FIG. 7A, theangle θ of the engagement wall 60 in the engagement protrusion 26 isapproximately 46.9 degrees from vertical on both third and fourthportions 64, 65 of the engagement protrusion 26. It is contemplated thatthe angle θ could be as low as 10 degrees or as high as 85 degrees. Asillustrated, the first and second portions 28, 32 of the engagementprotrusion 26 are not symmetrical, while the third and fourth portions64, 65 of the engagement protrusion 26 are generally symmetrical.

Referring again to the embodiments of FIGS. 3A and 7A, the inlet 70 andthe outlet 72 of the filter unit 12 have approximately the same diameterto dissipate extreme water pressure increases or decreases in thesystem. Nevertheless, it is contemplated that the diameter size of theinlet 70 and the outlet 72 could differ. Additionally, the engagementprotrusion 26 includes first and second seals 74, 76, wherein the firstseal 74 is disposed above the inlet 70 near a forward edge 78 of theengagement protrusion 26, and the second seal 76 is disposed between theinlet 70 and a base portion 82 of the engagement protrusion 26. Both thefirst and second seals 74, 76 extend around the sidewall 61 of theengagement protrusion 26. The first seal 74 keeps incoming unfilteredwater entering the inlet 70 from cross-contaminating with exitingfiltered water leaving the outlet 72. Therefore, the first seal 74 actsas a barrier, keeping the water to be filtered separate from thefiltered water. The second seal 76 acts as a barrier that preventsfiltered water from leaking around the body portion 14 during use.

Referring now to FIGS. 4 and 6-7, a shoulder 83 (FIG. 8) on the proximalend 16 of the filter unit 12 includes the laterally extending key member22, which is adapted to interface with and disengage an interferencemember 88 (FIG. 1) disposed in the filter head assembly 20, as outlinedin further detail herein. The laterally extending key member 22, asillustrated, includes a square shape. The laterally extending key member22 may extend out from the body portion 14 approximately 0.5 to 10 mm.In the illustrated embodiment, the laterally extending key member 22extends out from the body portion 14 approximately 2.75 mm. However, itis contemplated that the shape of the laterally extending key member 22could also be circular, oval, polygonal, etc. The laterally extendingkey member 22 includes a profile height that is adapted to be receivedin a key slot 24 inside the filter head assembly 20. The key slot 24includes three segments that define the key slot 24 shape. A firstsegment 85 (FIG. 11) is substantially linear and parallel with thelongitudinal extent of the filter head assembly 20. A second segment 87(FIG. 11) extends at an angel between 0 degrees and 98 degrees relativeto the longitudinal extent of the filter head assembly 20. A thirdsegment 91 (FIG. 11) extends substantially laterally or normal to thelongitudinal extent of the filter head assembly 20. The third segment 91may angle back 0 degrees to 25 degrees to provide a detent-typeconfiguration that is adapted to secure the laterally extending keymember 22 in place in the key slot 24 of the filter head assembly 20.Additionally, as shown in FIG. 13, a retention nub 91A may be disposedin the third segment 91 to assist in securing the laterally extendingkey member 22 in place.

As shown in the illustrated embodiment of FIG. 6A, the engagementprotrusion 26 may include a straight walled construction designed toengage the filter head assembly 20 and be received in a filter headsleeve 156. In an alternative embodiment, as illustrated in FIG. 6B, theengagement protrusion 26 includes a stepped construction including aledge 93 adapted to interface with a complementary receiving ledge 95(FIG. 17A) in the filter head assembly 20. This design ensures that thefirst and second seals 74, 76 disengage the filter head assembly 20 atthe same time.

As shown generally in FIGS. 4-10, first and second engagement surfaces90, 92 are disposed on the filter unit 12 on opposite sides thereof. Theillustrated embodiment depicts the first and second engagement surfaces90, 92 in the form of channeled grooves. However, it is contemplatedthat the first and second engagement surfaces 90, 92 could be formedfrom externally protruding walls, or a combination of grooves andexternally protruding walls, among other possible constructions. Thefirst and second engagement surfaces 90, 92 are adapted to engage firstand second guides 94, 96 (FIG. 11), respectively, juxtapositioned on aninterior wall 99 (FIG. 17) that defines a receiving cavity 100 (FIG. 18)of the filter head assembly 20. Similar to the laterally extending keymember 22, the first and second engagement surfaces 90, 92 are shownhaving a square shape. However, it is contemplated that the square shapeof the first and second engagement surfaces 90, 92 could also becircular, oval, polygonal, etc. Similar to the key slot 24, the firstand second engagement surfaces 90, 92 include three segments.Specifically, each of the first and second engagement surfaces 90, 92includes a first segment 102 that is substantially linear and parallelwith the longitudinal extent of the body portion 14 of the filter unit12. A second segment 104 of the first and second engagement surfaces 90,92 extends at an angle between 0 degrees and 90 degrees relative to thelongitudinal extent of the body portion 14 of the filter unit 12. In theillustrated embodiment, the angle Δ (FIG. 4A) of the second segment 104of the first and second engagement surfaces 90, 92 is 62 degrees fromvertical. A third segment 106 of the first and second engagementsurfaces 90, 92 extends substantially laterally or normal to thelongitudinal extent of the body portion 14 of the filter unit 12.Alternatively, the third segment 106 may angle back 0 degrees to 25degrees to provide a detent-type configuration that is adapted to securethe first and second guides 94, 96 in place after engagement of thefilter unit 12 with the filter head assembly 20. Each of the first,second, and third segments 102, 104, and 106 of the first and secondengagement surfaces 90, 92 provide a smooth engagement of the filterunit 12 with the filter head assembly 20 during installation of thefilter unit 12, as discussed in further detail herein.

As shown in FIG. 9, the first portion 28 of the engagement protrusion 26has a first radius of curvature. The second portion 32 of the engagementprotrusion 26 opposes the first portion 28 and has a second radius ofcurvature that is larger than the first radius of curvature. Thus, across-section of the engagement protrusion 26 taken perpendicular to thelongitudinal extent of the filter unit 12 is generally egg-shaped.Stated differently, the engagement protrusion 26 includes across-section with only one axis of symmetry. Further, the laterallyextending key member 22 is not aligned with, but instead is generallyoffset from, the inlet 70 of the engagement protrusion 26. The shoulder83 of the filter unit 12 is generally rounded. However, the shoulder 83can also be angled or have a more square construction. Alternatively,the shoulder 83 may include the shoulder support 89 that bears againstthe filter head sleeve 156. As shown in FIG. 10, the distal end 18 ofthe filter unit 12 is also generally rounded, but could include otherconstructions. A substantially planar portion 108 (FIG. 7A) is disposedat the distal end 18 of the filter unit 12, and allows the filter unit12 to be placed in an upright position.

Referring to FIG. 9A, the outlet 72 of the filter unit 12 isapproximately centered or aligned with a central longitudinal axis 109(FIG. 5) that extends centrally through the filter unit 12. A line fromthe central axis to the first portion 28 of the engagement protrusion 26is generally defined to be at an angle of zero degrees. The laterallyextending key member 22 is offset at an angle γ approximately 10 degreesfrom the first portion 28 of the engagement protrusion 26. The angle Φbetween the first portion 28 to the first segment 102 of the firstengagement surface 90 is approximately 26 degrees. The first segment 102includes an opening that extends across an angle η that is approximately15 degrees of the shoulder 83 of the filter unit 12. The firstengagement surface 90 extends across an angle β that is approximately104 degrees from the opening of the first segment 102 to an abutmentwall 106A adjacent the third segment 106. The first segment 102 of thefirst engagement surface 90 is approximately 180 degrees from the firstengagement surface 90 of the second engagement surface 92. The angle μtaken from a line defined between the central longitudinal axis 109 tothe second portion 32 is also 26 degrees. Thus, the angle between a linedefined between the central longitudinal axis 109 and the first portion28 to the first segment 102 of the second engagement surface 92 is 206degrees (180 degrees plus 26 degrees).

Referring now to FIGS. 11-16, the filter head assembly 20 includes afilter unit receiving end 118 and a water receiving end 119. The filterhead assembly 20 has a cylindrical receiver 120 that is defined by aninterior wall portion 120A (FIG. 17) and an exterior wall portion 120B.The cylindrical receiver 120 is adapted to receive all or at least aportion of the proximal end 16 of the filter unit 12. An externalcircumference of the interior wall portion 120A includes an inlet port122 (FIG. 18) and an outlet port 124 (FIG. 18) defined by opposing inletand outlet extension members 126, 128, respectively. The inlet extensionmember 126 defines an inlet aperture 126A. In the illustratedembodiment, the inlet aperture 126A is 0.3125 inches. The outletextension member 128 defines an outlet aperture 128A. In the illustratedembodiment, the outlet aperture 128A is 0.25 inches. The exterior wallportion 120B includes wall slots 129 (FIG. 18) that are sized togenerally accommodate the inlet and outlet extension members 126, 128.Although the inlet and outlet extension members 126, 128 are shown onopposite sides of the filter head assembly 20, it is contemplated thatthe inlet and outlet extension members 126, 128 could be at any anglerelative to one another and disposed at any position on the externalcircumference of the interior wall portion 120A. The cylindricalreceiver 120 includes an end wall 130 positioned on the cylindricalreceiver 120 proximate the water receiving end 119. Structural supports132 (FIG. 16) are disposed on an external surface of the end wall 130.An electronic connector extends from an edge of the cylindrical sidewall132 of the filter head assembly 20 and is adapted for engagement withthe electronic device 50 on the filter unit 12. Additionally, a clip 134is positioned on the exterior circumference of the filter head assembly20 and is designed to support an electronic connector 135 on the filterhead assembly 20. The electronic connector 135 is designed to receiveinformation from and communicate information to the electronic device50. The electronic connector 135 is removably connected with the clip134, such as by a snap-fit connection, with the clip 134. Thus, theelectronic connector 135 can be removed and replaced, if necessary.

Referring again to FIGS. 11-15, the key slot 24 is formed on an interiorside of the exterior wall portion 120B. The key slot 24, as mentionedherein, is designed to receive the laterally extending key member 22when the filter unit 12 is being inserted into the filter head assembly20. In addition, the interference member 88 forms a portion of theexterior wall portion 120B, and is designed to prevent a filter unitthat lacks a laterally extending key member from engaging the filterhead assembly 20. The interference member 88 includes an abutment catch136 (FIG. 17) disposed at a distal end of the interference member 88 atan interior side of the interference member 88. The abutment catch 136includes an abutment wall 137 (FIG. 17) and a sloped wall 138. Theinterference member 88 is connected to the exterior wall portion 120Bproximate the filter unit receiving end 118. A portion of the key slot24 extends along an interior side of the interference member 88. Asillustrated, the interference member 88 is connected with the exteriorwall portion 120B by a securing clip 140 (FIG. 18). The securing clip140 includes an aperture 141 (FIG. 18) adapted to receive a clipprotuberance 142 (FIG. 18) disposed on the interference member 88.However, it is contemplated that the interference member 88 could beconnected in other manners, such as by a living hinge, adhesive,mechanical fasteners, etc.

Turning now to FIGS. 17-19, the filter head assembly 20 also includes afilter receiver 150 with a stop member 151. The filter receiver 150 isrotatable inside the filter head assembly 20 between a filteringposition 152 (FIG. 22D) and a bypass position 154 (FIG. 20D), whereinunfiltered water passes through the filter head assembly 20 when thefilter unit 12 is not installed. The filter head assembly 20 alsoincludes the filter head sleeve 156, which has a cross-section thatcomplements the shape of the engagement protrusion 26. Generally stated,the cross-section of the filter head sleeve 156 is egg-shaped. Morespecifically, the filter head sleeve 156 includes a first portion 158that includes a first radius of curvature and a second portion 159opposing the first portion 158 that includes a second radius ofcurvature that is larger than the first radius of curvature. Thus, thefilter head sleeve 156 includes a cross-section with only one axis ofsymmetry. The filter head sleeve 156 is sized slightly larger than theengagement protrusion 26 such that the filter head sleeve 156 canclosely receive and retain the engagement protrusion 26 and maintain awatertight seal with the aid of the first and second seals 74, 76.

In an alternative embodiment, as illustrated in FIG. 17A, the filterhead sleeve 156 may include the stepped construction briefly mentionedabove with reference to FIG. 6A, such that the filter head sleeve 156includes the receiving ledge 95, which is adapted to engage and abut theledge 93 on the engagement protrusion 26. During insertion, the steppedconstruction of both the filter head sleeve 156 and the engagementprotrusion 26 allows the first and second seals 74, 76 to engage thefilter head sleeve 156 simultaneously. Similarly, during removal, thestepped construction allows the first and second seals 74, 76 todisengage the filter head sleeve 156 simultaneously.

Referring again to FIGS. 17-19, the filter receiver 150 includes afiltering pathway 155 and a bypass channel 157. The bypass channel 157allows water to flow through the filter head assembly 20 without beingfiltered. The filter head sleeve 156 of the filter receiver 150 isdisposed inside the filter head assembly 20. The inlet and outletextension members 126, 128 include couplings 160, 162 adapted tointerface with an inlet water conduit 172 and an outlet water conduit178, respectively. The coupling 160 includes an insert 170 that connectswith the inlet extension member 126. The insert 170 is sealed by agasket 174. The coupling 162 includes an insert 176 that connects withthe outlet extension member 128. The insert 176 is sealed by a gasket180. The gaskets 174, 180 of the inlet and outlet extension members 126,128, respectively, keep water from leaking out of the inlet and outletextension members 126, 128.

Referring to FIGS. 19 and 20A, during installation of the filter unit 12with the filter head assembly 20, the filter unit 12 is oriented suchthat the engagement protrusion 26 is aligned with the filter receiver150 and specifically aligned with the filter head sleeve 156, whichincludes an egg-shaped cross-section that complements the egg-shapedcross-section of the engagement protrusion 26, as outlined herein.Alignment of the engagement protrusion 26 with the filter head sleeve156 results in alignment of the laterally extending key member 22 withthe key slot 24, as well as alignment of the first and second guides 94,96 with the first and second engagement surfaces 90, 92, as shown inFIGS. 20B, 20C, and 20E. In this position, the abutment catch 136 on theinterference member 88 is in an interference position 200, as shown inFIGS. 20D and 20F. In addition, the engagement protrusion 26 is in onlyslight engagement with the filter head sleeve 156 of the filter receiver150, as shown in FIG. 20G.

Referring now to FIGS. 21A-21C, linear movement of the filter unit 12into the filter head assembly 20 generally occurs until the laterallyextending key member 22 begins to transition from the first segment 85into the second segment 87 of the key slot 24. At the same time, thefirst and second guides 94, 96 are transitioning from the first segment102 of the first and second engagement surfaces 90, 92, respectively,into the second segment 104 of the first and second engagement surfaces90, 92, respectively. As the laterally extending key member 22transitions into the second segment 87 and the first and second guidemembers 94, 96 transition into the second segment 104 of the first andsecond engagement surfaces 90, 92, the filter unit 12 begins to rotateclockwise into the filter head assembly 20. Because the second segment87 of the key slot 24 is at an angle relative to the longitudinal extentof the filter head assembly 20, and also because the second segment 104of the first and second engagement surfaces 90, 92 is at the samegeneral angle as the second segment 87 of the key slot 24, the filterunit 12 begins to draw into the filter head assembly 20, as shown inFIGS. 21B and 21C. At the same time, the engagement protrusion 26 hasengaged and is partially inserted into the filter head sleeve 156.Because the filter unit 12 is rotating into the filter head assembly 20,the engagement protrusion 26 subsequently rotates the filter head sleeve156 and the filter receiver 150 as the filter unit 12 is drawn into thefilter head assembly 20 (FIGS. 21D and 21E).

As shown in FIGS. 21A, 21B, and 21F, as the laterally extending keymember 22 passes through the second segment 87 of the key slot 24, thelaterally extending key member 22 passes by the interference member 88.As the laterally extending key member 22 passes by the interferencemember 88, the laterally extending key member 22 abuts the interferencemember 88 and forces the interference member 88 outward, thereby movingthe abutment wall 137 on the abutment catch 136 from the interferenceposition 200 to a non-interference position 202. When the interferencemember 88, and consequently the abutment wall 137 on the abutment catch136, is moved to the non-interference position 202, the stop member 151disposed on the filter receiver 150 is free to rotate past theinterference member 88, and consequently the abutment catch 136. Absentthe laterally extending key member 22, which abuts the interferencemember 88 and forces it outward, the abutment wall 137 on the abutmentcatch 136 would remain in the interference position 200, therebypreventing the stop member 151 on the filter receiver 150 from rotatingpast the interference member 88. Consequently, the filter unit 12 wouldbe unable to move from the bypass position 154 (FIGS. 20A-20G) to thefiltering position 152 (FIGS. 22A-22G).

Referring now to FIGS. 22A-22D, after the stop member 151 has clearedthe abutment catch 136 on the interference member 88, the laterallyextending key member 22 moves past the interference member 88 and beginsto transition into the third segment 91 of the key slot 24. At the sametime, the first and second guides 94, 96 transition into the thirdsegment 106 of the first and second engagement surfaces 90, 92. As thelaterally extending key member 22 engages a stop wall 204 in the keyslot 24, the first and second guides 94, 96 engage the abutment wall106A (FIGS. 22E and 22F) in the third segment 106 of the first andsecond engagement surfaces 90, 92. The retention nub 91A assists insecuring the laterally extending key member 22 against the stop wall 204of the key slot 24.

As shown in FIGS. 23-26, the filter unit 12 is now fully inserted intothe filter head assembly 20 and the bypass channel 157 has been fullyrotated out of alignment with the inlet extension member 126 and theoutlet extension member 128. Consequently, water that flows into thefiltering pathway 155 flows into the filter unit 12 through the inlet 70through the sidewall 61 and into the water filter 39. The water thenpasses through the filtering media 41 and into a central column of thefilter unit 12, where the water flows past the outlet 44 of the waterfilter 39 into the outlet 72 of the filter unit 12. The filtered waterthen passes into the filtered water pathway 155 of the filter receiver150 and exits out the outlet extension member 128 to a water line. Thewater line then relays the filtered water to a dispenser, where it isavailable for consumption by a user.

When the filter unit 12 is to be replaced, the filter unit 12 is rotatedcounterclockwise and the reverse steps disclosed above are conducted.Notably, the laterally extending key member 22 does not move theinterference member 88 out of the interference position 200 for the stopmember 151 during removal. This step is unnecessary as the stop member151 engages the sloped wall 138 of the abutment catch 136. Consequently,as a result of the sloped wall 138 construction, the stop member 151 isable to force the interference member 88 to the non-interferenceposition 202 without the assistance of the laterally extending keymember 22. The filter unit 12 is then rotated counterclockwise until thefilter unit 12 can be withdrawn in a linear motion from the filter headassembly 20.

In the illustrated embodiment, the water filter system 10 is adapted toreceive a filter unit 12, which is fully inserted by a quarter turninstallation. It is contemplated that the lengths of the segments of thefirst and second engagement surfaces 90, 92, as well as the lengths ofthe first, second, and third segments 85, 87, and 91 of the key slot 24may vary such that the turning radius may be greater than or less thanone quarter turn of the filter unit 12 relative to the filter headassembly 20.

It will be understood by one having ordinary skill in the art that thewater filter system 10, as described herein, can be used in a variety ofappliances, such as refrigerators, dishwashers, and clothes washers anddryers. Further, it will be understood that the water filter system 10can be used for a variety of applications, such as a second stage waterfilter for a dishwater, a water steam filter for an oven, and a watercleaning filter for consumption by a user out of a refrigerator. Theseare examples only and are not meant to be limiting.

The above description is considered that of the illustrated embodimentsonly. Modifications of the invention will occur to those skilled in theart and to those who make or use the invention. Therefore, it isunderstood that the embodiments shown in the drawings and describedabove is merely for illustrative purposes and not intended to limit thescope of the invention, which is defined by the following claims asinterpreted according to the principles of patent law, including theDoctrine of Equivalents.

The invention claimed is:
 1. A filter unit comprising: a body portionhaving a proximal end and a distal end; an engagement protrusionextending from the proximal end, the engagement protrusion having afirst portion that includes a first radius of curvature and a secondportion opposing the first portion that includes a second radius ofcurvature that is larger than the first radius of curvature; and aprotruding retention surface disposed on and extending radially outwardfrom the body portion, the protruding retention surface adapted tosecure the filter unit in a filter head assembly.
 2. The filter unit ofclaim 1, further comprising: a first recessed retention surface disposedon the body portion, the first recessed retention surface adapted tosecure the filter unit in the filter head assembly.
 3. The filter unitof claim 2, further comprising: a second recessed retention surfacedisposed on the body portion, the second recessed retention surfaceadapted to secure the filter unit in the filter head assembly.
 4. Thefilter unit of claim 3, wherein the first recessed retention surface andthe second recessed retention surface are on substantially opposingsides of the body portion.
 5. The filter unit of claim 1, furthercomprising: a central axis extending substantially centrally through thelongitudinal extent of the filter unit, wherein a first plane is definedbetween the central axis and the first portion of the engagementprotrusion and a second plane is defined between the central axis andthe protruding retention surface, and wherein the angle between thefirst plane and the second plane is approximately 10 degrees.
 6. Thefilter unit of claim 1, further comprising: a central axis extendingsubstantially centrally through the longitudinal extent of the filterunit, wherein a first plane is defined between the central axis and thefirst portion of the engagement protrusion and a second plane is definedbetween the central axis and the first recessed retention surface, andwherein the angle between the first plane and the second plane isapproximately 26 degrees.
 7. The filter unit of claim 1, wherein thedistance from a top edge of the engagement protrusion to the protrudingretention surface is approximately 41.2 millimeters.
 8. The filter unitof claim 2, wherein the distance from a top edge of the engagementprotrusion to the first recessed retention surface is approximately 62.8millimeters.
 9. A filter unit comprising: a substantially cylindricalbody portion having a proximal end and a distal end; an engagementprotrusion extending from the proximal end of the cylindrical bodyportion; first and second distinct retention surfaces disposed in thecylindrical body portion; and a third distinct retention surfacedisposed on and extending radially outward from the cylindrical bodyportion.
 10. The filter unit of claim 9, wherein the first and seconddistinct retention surfaces are defined by first and second groovesdisposed in the cylindrical body portion.
 11. The filter unit of claim9, wherein the distance from a top edge of the engagement protrusion tothe third retention surface is approximately 41.2 millimeters.
 12. Thefilter unit of claim 11, wherein the distance from a top edge of theengagement protrusion to the first retention surface is approximately62.8 millimeters.
 13. The filter unit of claim 10, further comprising: acentral axis extending substantially centrally through the longitudinalextent of the filter unit; and an outlet disposed on the engagementprotrusion, wherein the central axis extends through the outlet.
 14. Thefilter unit of claim 9, wherein the first and second distinct retentionsurfaces are disposed on substantially opposing sides of the cylindricalbody portion.
 15. A filter unit comprising: a body portion including anexterior wall and having a proximal end and a distal end; an engagementprotrusion extending from the proximal end, the engagement protrusionhaving a cross-section with only one axis of symmetry; and a retentionsurface disposed on the body portion, the retention surface defined byone of: a radially extending member that protrudes outwardly from thebody portion; and a groove defined in the exterior wall of the bodyportion.
 16. The filter unit of claim 15, further comprising: a centralaxis extending substantially centrally through the longitudinal extentof the filter unit, wherein a first plane is defined between the centralaxis and the first portion of the engagement protrusion and a secondplane is defined between the central axis and the retention surface, andwherein the angle between the first plane and the second plane isapproximately 10 degrees.
 17. The filter unit of claim 15, furthercomprising: a central axis extending substantially centrally through thelongitudinal extent of the filter unit, wherein a first plane is definedbetween the central axis and the first portion of the engagementprotrusion and a second plane is defined between the central axis andthe retention surface, and wherein the angle between the first plane andthe second plane is approximately 26 degrees.
 18. The filter unit ofclaim 15, wherein the distance from a top edge of the engagementprotrusion to a first gasket is approximately 2.7 millimeters.
 19. Thefilter unit of claim 18, wherein the distance from the top edge of theengagement protrusion to a second gasket is approximately 18.7millimeters.
 20. The filter unit of claim 18, wherein the distance fromthe top edge of the engagement protrusion to the retention surface isapproximately 41.2 millimeters.